Method of producing sheets of indefinite length composed of slitted wood veneer and a flexible backing



2,593,863 DINDEFINITE P" 1952 A. ELMENDORF METHOD OF PRODUCING SHEETS OF LENGTH COMPOSED OF SLITTE WOOD VENEER AND A FLEXIBLE BACKING Filed March 14, 1947 Patented Apr. 22, 1952 METHOD OF PRODUCING SHEETS OF IN- DEFINITE LENGTH COMPOSED OF SLIT- TED WOOD VENEER AND A FLEXIBLE BACKING Armin Elmendorf, Winnetka, Ill.

Application March 14, 1947, Serial No. 734,694

4 Claims.

Thick wood veneer that has a flexible backing, such as heavy paper, has many uses, particularly in the building field. Because veneers are thin compared with lumber commonly employed, much less wood is required to cover a given area with the composite material than with ordinary lumber, thereby achieving not only a saving in cost, but also compensating for shortages in lumber.

Panels made of wood veneer having a thickness of about three sixteenths inch, backed with tough paper, have been found to be satisfactory for housing when the veneer is partially divided by slitting it into narrow strips, usually about one half inch wide, with the division lines running in the general direction of the wood grain; space for expanding being obtained when the slits are widened to spread the strips apart from each other about ten to thirty thousandths of an inch for strips one half inch wide.

The primary object of the present invention is to produce a simple and novel process to make possible the manufacture, at a relatively high speed, of a continuous sheet of thick wood veneer, backed with heavy paper, the veneer being expanded by slitting to make it suitable structurally for wall panelling.

The process may be one in which the veneer is fed continuously or one in which it is fed intermittently; the bonding of the veneer and the backing in the latter instance being effected during the periods of rest of the veneer. In a companion application, filed on even date herewith and entitled Machine for Producing Sheets of Indefinite Length Composed of Slitted Wood Veneer and a Flexible Backing, said application being filed as Serial No. 734,695, on March 14, 1947,

I have disclosed a simple and novel machine for carrying out my new method; that particular machine operating on the principle of an intermittent feed for the veneer. In the present application I shall describe both forms of my process independently of such automatic machinery as will ordinarily be used for carrying out the process.

The various features of novelty whereby the present invention is characterized will hereinafter he pointed out with particularity inthe claims, but, for a full understanding of the invention and of its objects and advantages, reference may be had to the following detailed de scription taken in connection with the accompanying drawing, wherein:

Figure 1 is a diagram illustrating the slitting and expanding of a sheet of wood veneer and the bonding thereof to a flexible backing in accordance with what may be termed the continuous form of my improved process; Fig. 2 is a diagram illustrating the manner of manipulating the slitting blade of Fig. 1; Fig. 3 is a face view of a fragment of the product of my improved process, parts being broken away to show the diiferent layers; Fig. 4 is a view similar to Fig. 1, with the roll of paper and glue-applying means omitted, illustrating the other, or intermittent, form of the process; Fig. 5 is a plan view of the wood component of the structure herein shown; and Fig. 6 is a sectional view of the structure taken on the line 6--6 of Fig. 5.

Referring first to Figs. 1, 2 and 3, l represents a table on which one end of a long sheet A of thick wood veneer, with the wood grain running crosswise thereof, is laid and from which it is fed into and through a battery of hot rolls {2. The heated sheet moves ahead over an anvil 3 which, preferably, is a transverse idler roller free to turn. A blade 4, extending across the width of the sheet, is driven down into the veneer on a line directly above the anvil and parallel-to the axis of the latter. The blade preferably has about a 20 bevel at the cutting edge so that, when it enters the wood, it cuts a slit and exerts a wedging action to widen the same until the uncut portion of the wood in line with the cutting edge is stressed beyond the rupture point; the sheet being thus expanded and divided at the slit except for the presence there of uncut strands that hold the veneer on opposite sides of the slit together. When the blade is manipulated so as to cut slits half an inch apart, the expansion effected by slitting should be about 2% to 6%.

Since the blade must remain in the wood an appreciable time While making each slit, I so manipulate it that the blade and the veneer travel ahead together during such periods, relieving both of any stresses that would be induced by a forward pull on the blade by the veneer. In Fig. 2, X represents the plane of the upper face of the veneer sheet and Y represents the'path, in space, followed by the blade from the time it descends to such plane and, after doing its work, rises up clear of the veneer.

The slit, expanded veneer sheet is moved on from the slitting zone into a laminating zone,

going from 2% to 6% faster than its speed while approaching the slitting zone. In the laminating zone are pairs of pressure rollers 6 between each pair of which the veneer passes. A sheet of paper P is carried up over the first roller 6 of the lower group of laminating rollers; the paper having adhesive on the face that is uppermost at the time of being engaged with the under side of the veneer sheet. The paper may be supplied in the form of a large roll P from which it is unwound and passed through a glue-applying apparatus 7; being thus coated on one side with an adhesive Q on its way to the roll 6*.

By heating the veneer before the backing zone is reached, a good bond between the same and the backing can be obtained in a few seconds required for passing through the battery of laminating rollers.

A fragment of the finished product is shown in Fig. 3, A being the veneer, a the expanded slits therein, P the paper and Q the adhesive that unites the paper and the veneer.

In Fig. '4, which illustrates the intermittent process, 8 is a table to support a stack of pieces of wood veneer as long as the width of the sheet to be produced and having glue on their long edges, laid crosswise of the table; the wood grain, of course, extending lengthwise of the pieces. These pieces are pushed, long edge to long edge, into a hot plate press 9 against a resistance that insures good contacts between such edges. The feeding of the veneer elements may be carried out by using two endless belts Ill and ll, one above the other, the lower belt reaching from the table to the vicinity of the press, while the upper belt stops short of the table to leave that part of the upper run of the lower belt adjacen to the table exposed. Pieces of veneer A may be laid on the exposed part of belt I I and be carried along by the latter until gripped between the same and the lower run of the upper belt ID. The pres must be open while the veneer is moving ahead, and forward movement of the veneer must cease just before the press closes on it. In order to maintain edge to edge contact between the pieces of veneer that enter the press, resistance may be set up to the forward movement that the belts seek to give the pieces of veneer. This may conveniently be accomplished by clamping feed rollers l2 and I3 that lie beyond the press and move the veneer ahead at a lesser speed than that of the belts. This insures that the sheet is slowed down upon leaving the press so that each following piece of veneer is eventually driven into firm engagement with the piece just ahead of the same; the belts slipping relatively to the more slowly moving pieces while bringing up further pieces which are still moving faster than the r closing the same, and the heat from the press,

produce a firm bond in a few seconds when a fast setting adhesive, such as urea adhesive, is used. Upon leaving the edge-gluing press, the now continuous sheet of veneer, which is the sheet material A of Fig. 1, enters and passes through the same slitting zone as that in the continuous process; the slitting in both processes being accomplished while the veneer is moving ahead.

The paper backing P is fed into engagement with the under side of the hot, slit veneer sheet in the manner previously described. The laminating is effected, however, in a second hot plate press 24 that opens and closes in synchronism with press 9. Leaving the laminating press in the form of a flexible two-ply sheet B, the final product, fed onward by clamping feed rollers I5 and !6, may be cut into any desired lengths or may be wound into a roll B of any desired size. The rollers i5 and it of course pull the laminated sheet ahead at a speed of about 2% to 6% stresses set up in any strip are not transmitted to the strips on either side thereof. Furthermore, in the second form of the process, the larger veneer sheet is progressively built up at one end whileundergoing laminating at the other end, effecting a great saving in time and in the ultimate cost of the finished product.

I wish to emphasize that when, in the course of my method, I slit and distend the wood, I separate the veneer ply only partially into narrow strips. The strips are preferably connected by fibres or uncut strands that hold together the veneer on opposite sides of each slit. However, the uncut portion of the wood is stressed beyond the rupture point, and the structure of the wood is thus broken, even though the uncut strands extend across the slits and provide a partial or limp connection between adjacent pieces or strips of veneer.

I claim:

1. The method of treating wood veneer which comprises conveying a sheet of Wood veneer through a zone of treatment, slitting it, as it passes through the zone of treatment, along parallel lines extending generally along the grain of the wood, and, simultaneously with the slitting, exerting a longitudinal thrust against the slit portion, in the direction of movement of the sheet, while conveying the slit portion of the sheet at a speed somewhat greater than the speed of feed of the unslit portion of the sheet into the zone of treatment, thereby increasing the acrossthe-grain dimension of the sheet.

2. The method of producing a composite, flexible, two-ply sheet composed of Wood veneer and a backing therefor, with the wood grain extending crosswise of the sheet, which comprises moving an unslit sheet of wood veneer crosswise of its grain at a predetermined speed into a slitting zone, successively slitting the sheet along parallel spaced lines extending in the general direction of the grain of the veneer, into narrow strips connected by uncut strands, and moving the slit part of the sheet at a speed that is from two to six percent greater than said predetermined speed at which the unslit part is moved, and bonding a flexible backing to the slitted veneer, as it passes beyond said slitting zone.

3. The method of treating wood veneer which comprises conveying a sheet of wood veneer continuously into a slitting zone, progressively slitting it, as it passes through said slitting zone in a spaced succession of slits, with individual slits extending substantially continuously from edge to edge of the sheet, along parallel lines extending generally along the grain of the wood, and moving the separated slits beyond and away from the slitting zone at a speed slightly exceeding the movement of the wood veneer to the slitting zone, and thereby somewhat increasing the across-thegrain dimension of the wood veneer.

4. The method of treating wood veneer which comprises conveying a sheet of wood veneer continuously into a slitting zone, progressively slitting it, as it passes through said slitting zone in a spaced succession of slits, with individual slits extending substantially continuously from edge to edge of the sheet, along parallel lines extending generally along the grain of the wood, and, simultaneously with the slitting, exerting a Wedging action sufiicient to spread the slits and rupture the wood along the slits, while leaving uncut connecting strands, whereby the sheet is transformed into one that is somewhat wider and is composed of strips held together by uncut strands, and moving the separated slits beyond and away from the slitting zone at a speed slightly exceeding the movement of the wood veneer to the slitting zone, and thereby somewhat increasing the 15 6 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,937,858 Taber Dec. 5, 1933 1,944,282 Snyder Jan. 23, 1934 2,220,958 Jennings Nov. 12, 1940 2,323,105 Welsh June 29, 1943 2,336,852 Elmendorf Dec. 14, 1943 2,344,488 Bowling Mar. 21, 1944 2,379,258 Smith June 26, 1945 2,454,787 Francek Nov. 30, 1948 

